A variety of tree-trimming apparatus have been developed for clearing tree branches and other vegetation, particularly that which is difficult to reach with conventional hand-held equipment. One approach has utilized a person-carrying bucket that is raised by means of a boom to the area of unwanted growth. The vegetation is then cut by hand or power saw by the person or people in the raised bucket. Such an operation, however, may present dangers to the workers in the form of falling tree branches and electrocution in the event that vegetation is being trimmed from an area near active power lines. In addition, raised bucket systems typically have limited range when the person-carrying bucket is in the lifted operating condition. As a result, elevated vegetation-cutting operations often require multiple movements of the base vehicle, which cannot be safely accomplished while the person is positioned in the elevated bucket. Consequently, each movement of the base vehicle must be preceded by a lowering of the bucket to its storage and travel position, which substantially increases the time required for completing a tree-trimming project.
Other devices have been proposed which alleviate some of the drawbacks of bucket lift systems. For example, machines employing retractable/extendable booms have been implemented with a remotely-operated cutting device on the end of the boom. The boom device is mounted on a vehicle to enhance the cutting apparatus mobility. Some of such conventional devices, however, have limited reach and stability rendering such cutting apparatus ineffective in clearing vegetation from high locations. Certain models with extended boom reach require the use of outriggers mounted on the sides of the vehicle to stabilize the apparatus from tipping due to the large weight and relatively high center of gravity introduced by relatively long booms. Because the stabilizing outriggers must be accurately re-positioned each time the vehicle is moved, overall project time is substantially increased, reducing the efficiency of apparatus requiring stabilizing outriggers to level and establish a stable vehicle for support of the cutting boom.
Many of the drawbacks of conventional tree-trimming apparatus were resolved in the system described in U.S. Pat. No. 4,411,070, herein incorporated by reference. The apparatus of the '070 patent provides an efficient tree-trimming system utilizing a telescopic and pivotal boom for enhanced mobility of the cutting device secured at the end of the boom. In addition to the extensibility of the device of the '070 patent, the boom is constructed from a light-weight electrically nonconductive flexible material such as fiberglass. Such construction is lightweight and allows the tree trimming apparatus to be used without the necessity of outriggers mounted on the vehicle for stabilization. The electrically nonconductive boom also provides a safer working environment for the operator, since there is no conductive path between the end of the boom and the operator.
While the apparatus of the '070 patent has proven to be an effective tree-trimming system, a need has emerged for trimming vegetation that is inaccessible to large vehicles. Examples include vegetation surrounding power lines that are not located along a roadway, and residential applications in which elevated vegetation cutting is required but not accessible by the vehicles which support conventional extended-boom cutting devices. Efforts have been made to substantially reduce the size of the support vehicle, to, for example, facilitate passage through a residential gate opening (e.g. 36 inch wide opening). However, the reduction in size of the support vehicle correspondingly reduces the stability of the support vehicle when elevated cutting operations are commenced. The standard approach to address such instability is the use of outriggers, as described above. Such outriggers, as also described above, however, limit the ease of mobility of such apparatus, and substantially reduce the efficiency of operation because the outriggers must be carefully (and oftentimes manually) positioned at each cutting area. Because typical projects involve several distinct cutting areas, conventional systems require multiple setups and repositioning of outriggers, which consumes substantial time resources.
In view of the above, therefore, it is an object of the present invention to provide a compact mobile tree-trimming apparatus which does not require the use of outriggers while nevertheless providing a stable and mobile base for supporting extended boom cutting operations.
It is a further object of the present invention to provide a mobile tree-trimming apparatus that is sufficiently compact to be useful in confined spaces, including by passing through conventional residential gate openings of 36 inches.
It is a still further object of the present invention to provide a mobile tree trimming apparatus which may be remotely operated from a safe distance.
It is yet another object of the present invention to provide a compact mobile tree trimming apparatus that is capable of operating from uneven and inclined ground surfaces.